Optical scanning apparatus

Abstract

An optical scanning apparatus includes a rotatable polygonal mirror for deflecting first and second laser beams, which are incident on the polygonal mirror at diff(rent positions with respect to a rotational direction of the polygonal mirror; a first optical member for transmitting the first laser beam; a second optical member for transmitting the second laser beam; a laser beam blocking member, disposed between the first optical member and the second optical member, for blocking the first laser beam reflected by the first optical member to prevent the first laser beam reflected by the first optical member from being incident on the second optical member.

1. An optical scanning apparatus comprising:
 a rotatable polygonal mirror for deflecting first and second laser beams, which are incident on said polygonal mirror at different positions with respect to a rotational direction of said polygonal mirror; 
 a first optical member for transmitting the first laser beam; 
 a second optical member for transmitting the second laser beam; and 
 a first laser beam blocking member, disposed between said first optical member and said second optical member, for blocking the first laser beam reflected by said first optical member to prevent the first laser beam reflected by said first optical member from being incident on said second optical member. 
 
   
   
     2. An apparatus according to  claim 1 , wherein said first laser beam blocking member is disposed between said polygonal mirror and said second optical member. 
   
   
     3. An apparatus according to  claim 2 , wherein a distance between said first laser beam blocking member and said polygonal mirror is not less than 5 mm. 
   
   
     4. An apparatus according to  claim 2 , further comprising a second laser beam blocking member, disposed between said polygonal mirror and said first optical member, for blocking the second laser beam reflected by said second optical member to prevent the second laser beam reflected by said second aperture member from being incident on said first optical member. 
   
   
     5. An apparatus according to  claim 4 , wherein said first and second laser beam blocking members are integral with each other. 
   
   
     6. An apparatus according to  claim 1 , wherein said first laser beam blocking member includes a slit for permitting the second laser beams to pass toward said second optical member. 
   
   
     7. An apparatus according to  claim 1 , wherein said first and second laser beams are incident on said polygonal mirror in directions crossing with a rotational plane of said polygonal mirror. 
   
   
     8. An apparatus according to  claim 7 , wherein said first and second laser beams are crossed with the rotational plane of said polygonal mirror in opposite directions. 
   
   
     9. An apparatus according to  claim 1 , wherein the first laser beam and the second laser beam are incident on opposite surfaces of said polygonal mirror. 
   
   
     10. An apparatus according to  claim 9 , wherein said first optical member and said second optical member are disposed at positions substantially symmetrical with respect to a rotational center of said rotatable polygonal mirror. 
   
   
     11. An electrophotographic apparatus comprising:
 a scanning optical apparatus according to  claim 1 , which emits first and second laser beams; and 
 first and second photosensitive members; 
 wherein said first photosensitive member is imagewisely exposed tote first laser beam, and said second photosensitive member is imagewisely exposed to the second laser beam.